General Description: If a port is declared as "std_logic_vector (0 downto 0)" in a VHDL source file, the VHDL testbench generated by Project Navigator shows the port as "std_logic".
This will cause the following warning to be reported in ModelSim:
"# WARNING[1]: file.vhd(xx): Types do not match for port xxx."
The simulation will not start due to a type mismatch (binding) error.
Solution
If a testbench is to be generated by Project Navigator, "std_logic_vector (0 downto 0)" cannot be used in the source. The source port must be changed to "std_logic".
This issue has been fixed in the 5.1i release of the software.